Miochol (Acetylcholine Chloride)

Miochol, a direct‑acting muscarinic agonist, is used in ophthalmic procedures that require pupil constriction.

• Intraoperative miosis: produces a small pupil to improve access and visualization during cataract extraction, trabeculectomy, and other intraocular surgeries.
• Diagnostic pupillary testing: temporarily constricts the pupil to assess muscarinic receptor function in ophthalmic examinations.
• Gonioscopic facilitation: creates a constricted pupil that enhances angle visualization during anterior chamber angle assessment.

• Acetylcholine chloride binds directly to muscarinic receptors on the iris sphincter muscle, activating G‑protein coupled pathways that increase intracellular calcium. This triggers contraction of the sphincter, resulting in pupil constriction (miosis) and promotes outflow of aqueous humor, thereby aiding intra‑ocular pressure regulation during surgical manipulation.

Miochol may cause ocular and systemic reactions after administration.

Common Side Effects

• Blurred vision: transient loss of visual clarity due to pupil constriction.
• Eye pain or discomfort: mild irritation at the site of instillation.
• Increased lacrimation: excessive tearing following the drop.
• Headache: mild headache associated with ocular muscle spasm.
• Brow ache: discomfort around the eyebrow region.

Serious or Rare Side Effects

• Severe ocular inflammation: uveitis or iritis requiring immediate medical attention.
• Corneal ulceration: damage to the corneal epithelium that can lead to vision loss.
• Systemic cholinergic effects: bradycardia, hypotension, bronchospasm, or excessive salivation.

Before using Miochol, consider the following safety measures.

• Assess ocular health: confirm absence of active infection or severe inflammation.
• Avoid in narrow‑angle glaucoma: pupil constriction may precipitate angle closure.
• Monitor systemic cholinergic signs: watch for bradycardia, hypotension, or bronchospasm.
• Use with caution alongside anticholinergic agents: may reduce efficacy.
• Prevent contamination: use sterile technique and discard after the recommended period.
• Store at room temperature: keep in the original container, protect from light and moisture.

Miochol can interact with other medications that affect cholinergic pathways.

Major Interactions (Avoid)

• Systemic anticholinergics (e.g., atropine): may antagonize Miochol's miotic effect.
• Cholinesterase inhibitors (e.g., pyridostigmine): can potentiate ocular cholinergic activity, increasing risk of adverse effects.

Moderate Interactions (Monitor Closely)

• Other ocular miotics (e.g., pilocarpine): additive miosis may lead to excessive constriction.
• Topical anesthetics: may enhance corneal absorption of acetylcholine.
• Systemic cholinergic agents: monitor for signs of systemic cholinergic excess.